This guest post comes from Marc Mezzacca, founder of NextGen Shopping, a company dedicated to creating innovative shopping mashups. Marc’s latest venture is a social-media based coupon code website called CouponFollow which utilizes the Twitter API.

Last month Google announced it was killing off several products, perhaps most notably Google Reader. Caught in the mix, and perhaps somewhat under the radar, was also notice of the deprecation of their shopping search API. In the official blog post Google writes:

"We’re deprecating our Search API for Shopping, which has enabled developers to create shopping apps based on Google’s Product Search data. While we believe in the value this offering provided, we’re shifting our focus to concentrate on creating a better shopping experience for users through Google Shopping. We’ll shut the API down completely on September 16, 2013."

Come Fall time of this year it will affect a number of developers who have already used the API to build websites, mobile apps and other shopping related apps with Google's data. This includes those developers and web publishers using it in conjunction with the Google Affiliate Network for monetization. According to a discussion in the Google Search for Shopping API group, Google initially issued a statement claiming it would continue to support publishers in the Google Affiliate Network. They have since retracted this claim, which has caused concern for publishers in their affiliate network, and whom now must look for alternatives

A relatively new provider, YC-Backed Semantics3, couldn't have asked for a more opportune moment to showcase their solution. Whereas Google requests that merchants upload their information through a shopping feed, Semantics3 organically crawls e-commerce websites, and offers up a robust product search API as their business model. Semantics3 co-founder Varun Sivamani has already begun helping developers migrate their product from Google to the Semantics3 platform.

Skimlinks, a content monetization platform for web publishers, also has a product search API which was launched last year. However, the data included is limited to e-commerce websites which have an affiliate program, and is not as robust as what Google had offered, or what Semantics3 offers now.

It has been less than three years since the predecessor, Google Base, was deprecated, and Google Search for Shopping was announced as a part of the replacement. It seems that this time around no replacement will come from Google, who is apparently shutting the door completely on developers wishing to access to their shopping data.

This comes as a good reminder that you should have a backup strategy in place should your relationship with your primary data provider go sour. While it may appear safe to build on top of a well established company like Twitter or Google, let me remind you again that building your business on top of others' data is always a risk. As a company's priorities change so will their rules to data access. Luckily, for those who have built their businesses on top of Google’s data in this particular scenario, at least some alternatives exist.

Update: As of yesterday evening Google has decided to close down their entire Google Affiliate Network service as well, coming as a surprise to both affiliates and advertisers. Support and operation will continue until July 31st of this year. For more details see the Google Affiliate Network blog at http://googleaffiliatenetwork-blog.blogspot.com/